Saturday, November 26, 2016

Genetics--King of Domestication

Our recent blog posts have highlighted the human agricultural revolution which occurred about 10-12,000 years ago. The transitions were not uniform in all areas. Some changes had begun earlier in an era when human population growth was limited. The full scope of the agricultural revolution, however, delivered a positive jolt to human population growth. Human societies changed.

Many changes have been spectacular. A problem in modern biology consists of understanding the changes that shape the diversity of our natural world. The modifications of plants and animals during the course of the agricultural revolution were not major alterations of DNA structure. The phenomenon of animal and plant domestication does not produce a new species, but involves significant changes in genetics. One oft-repeated term is, “It’s in my genes.” A gene is a small “stretch” of DNA. Genes comprise only 1% of the three billion nucleotide letters of the huge DNA molecule, but small differences in genes can make a large difference in what biologists term an organism’s phenotype, the physical expression of an animal or plant.

Genes are components of chromosomes. Animals and plants have two sets of chromosomes—one from each parent. They are known as diploid. When both chromosomes contain identical genes at a given location, they are termed homozygous. If they contain different genes for a given trait at the given location, they are termed heterozygous. Variant forms of two different genes are termed alleles which sometimes result in diverse physical manifestations in their offspring. Early human agriculturists noticed these different traits and selected individuals with the most desired variations to reproduce. Over long periods of time the new traits became more and more manifest as the process of selection proceeded. The population changed somewhat but did not become a new species. Chromosomes have many genes which act to produce many proteins—physical building blocks of an animal or plant.

 As we look back on animal and plant domestication coming into play fairly suddenly about 10,000 BC, some questions occur. During the existence of full humanity extending back several tens of thousands of years, nothing like the agricultural revolution had occurred in human history. Until then the modern fully human population had been limited by Earth’s ice age climate. The Garden of Eden could have been located in the Persian Gulf area  during the Ice Age when sea level was considerably lower. Earth’s temperatures close to the equator were mild, unlike the Ice Age climate in the northern US Midwest and northern Europe. Theologians who see Adam and Eve as a literal, initial couple according the scriptural account of man’s origin, and secular paleontologists who have postulated a sort of population bottleneck somewhere in the area of the Middle East share some measure of agreement based on the evidence of human paleontology.

Plant and animal domestication since 10,000 BC has changed the landscape of hundreds of living organisms with which man has interacted. In some cases the domesticated plant or animal is considerably different from the pre-domesticated organism even though the domesticant is still the same species because they were able to interbreed with the original species. Were humans to travel back 12,000 years in time, he would perceive that many organisms alive in that day were very different. Human agriculturists have succeeded in substantially altering the organisms’ phenotypes.

Humans at the beginning of the agricultural revolution did not understand the workings of genetics. However they did discover that application of artificial selection of certain specimens with desirable traits resulted in different improved traits in their offspring when repeatedly selected over many generations. In prehistoric times it made sense to select the fittest specimens to reproduce. Most often animals were selected for their more docile behaviors and more favorable interactions with humans. Later agriculturalists also selected plants and animals for more abundant, attractive, convenient, useful, or tasty products they supplied.

The website writer K. Kris Hirst has produced thoughtful and informative articles concerning the domestication phenomena of plants and animals. From her site  “Animal Domestication—Table of Dates and Places” we quote: “Animal domestication…is a millennia-long process that creates the mutually beneficial relationship that exists today between animals and humans…All of the animals that we share our lives with today, such as dogs, cats, cattle, sheep, camels, geese, horses, and pigs, started out as wild animals but we changed them over the hundreds and thousands of years into more sweet-natured and tractable partners in farming.” One of Hirst’s most colorful quotes describes, “…changing the lean, nasty wild boar into a fat, friendly farm animal.” Many changes resulting from domestication in the world of plants have been even more phenotypically spectacular.

Is domestication an example of organic evolution? Notwithstanding the ambiguous analysis of evolutionists, we propose it is not. The accepted modern textbook meaning of organic evolution has very specific implications. It is a naturalistic theory which does not include a hint of original or ongoing divine miracle. Some theistic evolutionists claim God oversees the process of natural selection acting in concert with mutation to produce a new species and ultimately many millions of new species. Naturalistic evolutionists do not see God overseeing or standing by to observe the developmental process—God is not part of the equation at all. In their view, every living thing descended from a common ancestor. In effect, the expressions molecules to man, particles to people, or life from non-life, some of which are meant to be humorous, describe the essence of the belief system of naturalistic evolution.

In contrast, humans’ artificial selection process resulting in domestication of animals and plants is an intelligently designed feature of Earth’s living things. If God has created all things, we may see the outcome of generations of human artificial selection as a gift of the Creator enabling humanity to “subdue the earth” as commanded in Genesis 1:28. Our blog recognizes healthy “evolution” defined simply as change. The Creator enables man to accomplish healthy change in animals and plants to enhance the quality of his existence.